This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Multi-edge XAS characterization of hetero-binuclear inorganic model complexes and metalloprotein active sites are proposed to define the key geometric and electronic structural features of purple acid phosphatases. Data will be collected for a series of FeIIIMII complexes, where M=Mn, Ni, Cu, Zn, at each metal K- and L-edges for EXAFS and XANES analysis that are biomimetic analogues of the metalloprotein active site. The XAS results will be correlated with small molecule crystallographic data and electronic structure calculations. These inorganic model complexes will provide the background for the analysis and interpretation of FeIIIMnII containing purple acid phosphatase samples at various pH values. The bridging O-ligand between the two metal center is expected to play an important role in catalysis as the nucleophile in catalysis. The molecule understanding of chemical function of purple acid phosphatase is expected to generate new ideas for drug development related to metabolic disfunctions, such as bone resorption.